1. Field of the Invention
The present invention relates to a tyre for vehicles. More particularly, the invention applies to High Performance and Ultra High Performance cars and racing cars, in particular cars for rally driving, having high handling qualities.
2. Description of the Related Art
Optimal features in terms of traction power and grip performance on braking as well as handling on dry and wet roadway surfaces and satisfactory wear resistance are usually required from tyres of this class.
Known are tyres for vehicles having a tread provided with blocks confined by circumferential grooves, extending in a substantially longitudinal direction, and transverse grooves extending in a substantially axial direction. The blocks resulting from interlacing of said grooves have several different shapes that are suitably studied and disposed in circumferential side by side rows, each of which is enclosed between two subsequent circumferential grooves.
The circumferential grooves can affect the steering and steady running properties of the tyre in relation to lateral thrusts (slip thrusts) directed parallel to the rotation axis of the tyre itself.
The transverse grooves, in turn, can affect the tyre traction power, i.e. the capability of efficiently receiving the tangential thrusts parallel to the running direction from the roadway surface, during the acceleration and braking steps of the vehicle.
The circumferential and transverse grooves can also affect draining of the water in the contact area with the roadway surface (footprint area) during running on a wet roadway.
WO 2006-007877, in the name of the same Applicant, proposes a tyre the tread band of which has at least one first and one second circumferential grooves separating a central portion from two shoulder portions. To some distance from at least one of the circumferential grooves, a circumferential cut is formed. The tread band is crossed by transverse grooves distributed in repeated circumferential modules, each of which in at least one shoulder portion has a main groove having a first substantially rectilinear segment inclined at an angle included between 3° and 10° relative to a radial plane of the tyre, a second substantially rectilinear segment extending between the circumferential cut and the first circumferential groove at an angle included, just as an indication, between 105° and 130° relative to the radial plane, and a curvilinear portion for connection between the first and second segments.